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The IRC does not specifically approve of PVC or any kind of plastic venting. The code recognizes listed venting, which means listed to UL 1738, such as AL29-4c stainless steel or per mfrs. instructions. Now, most mfrs simply say you can use Sch 40 pvc. They don't get into specifics of joining, support, etc. So, where do these regs. for purple primer come from? Local ordinances. The inspectors want to CYA. This became more of an issue in the wake of the Lofgren carbon monoxide case in Aspen, CO where PVC was not properly joined.

FYI, Charlotte pipe DOES require primer on Sch 40 PVC. Download the installation instruction and see page 89. The primer softens the plastic for a better, more uniform bond.

As for the 'ugly' stains, that's a reflection of workmanship. I've posted on this before but here's the trick: wrap the pipe with blue painter's tape revealing a 1/8"-1/4" uniform band. Prime to the tape, apply cement, join and pull the tape. You get a pretty purple ring everytime and only takes an extra few seconds.

If something goes wrong and you are called in, you'd better be following the mfrs instructions on joining.

Back to the 'approval' issue for venting: None of the major mfrs. have 'approved' their pipe for combustion venting. There is no ASTM std. to test their pipe to for venting. This is a major reason we have not been able to agree on a new listing std. on the UL Standards Technical Panel the way the Canadians have with their S636 listing. We see too many problems with their listing.

With a max. operating temp. of 140F, you'be do well to perform combustion analysis to ensure it is not too hot for the venting. BTW, I called Fernco and they say the same as Charlotte pipe: 140F max continuous and not approved for venting even though their couplings are used in this application and even sold to Bradford White for their TTW water heaters.

Fixing Stupid:

You can't fix it (stupid) and you can't make installers do it properly. I've seen PVC venting on direct vent water heaters that were a lovely shade of brown. Meaning that the chorides have been leaching out of the pipe and fittings. The whitest part of the pipe and fittings were where the PVC cement was on the pipe.

That's a lot of work to tape the pipe so you can keep the purple stain off the pipe. Then, to remove it. Time = Money. If you clean pipe with clear cleaner and wipe it off with a clean rag, you will be able to tell if the job was cleaned by the fact that there will be missing colored manufacturers mark on a large amount of fittings that are visable where the line is facing the observer. Then, close nipples shouldn't have any line. Most of the pool piping I see where I work isn't cleaned, cut off straight or de-burred. And cut off with a 6 Pt sawzall blade. How do you accurately measure pipe that is cut off crooked?

We're talking work that would be proudly shown on "The Wall Of Fame". Not something that someone saw that would be a good candidate for the "Wall Of Shame. I like to think my work could be found on the Wall Of Fame".

The case you mention in Colorado. I'll bet that threre was no mention of deburring the pipe so the pipe doesn't wipe the cement out of the socket like a windshield wiper does on a car in the rain. When PVC was first introduced in Massachusetts in the 60's, the instructions required square cuts and deburring. I've pulled apart leakers that were none of the above and not cleaned. Then, crooked cuts that popped back out so there was only 1/4" inserted on the short side.

I guess it comes under the topic of good installers have to suffer from the shoddy practices of a few.

That's a lot of work to tape the pipe so you can keep the purple stain off the pipe. Then, to remove it. Time = Money. If you clean pipe with clear cleaner and wipe it off with a clean rag, you will be able to tell if the job was cleaned

If you're not sniffing the primer before using it, it shouldn't be too hard to apply it neatly.

Also you are not supposed to wipe off the primer. The solvent should be applied while the primer is still wet

Cleaning:

Am I on trial here?

I know what it says on the can. I know what it said on the can in the 1960's Do you?

I clean the pipe and fittings. I clean it off with a rag, I clean it off until any stains or any other things are off it. I never have leaks. I also chamfer the pipe. It doesn't tell you to do that anymore. I see a lot of fittings that haven't seen anything but cement. When I have used purple primer, the glaze is still on the pipe when I wipe it off.

You do it your way and I'll do it mine. If I start getting leaks, I'll figure it out and make changes.

Its like using Teflon Tape on fuel oil lines. Pump manufacturers lobbied AHJ;s to ban it. I recently re-piped two leaking Shutts oil tanks. Some fittings leaked badly when the tanks were filled. They used some form of blue loc thread sealer. It took two, 3' pipe wrenches to get the leaking fittings apart. The blue stuff was so hard that I couldn't get it off with a utility knife. I repiped it all with Blue Monster Teflon tape and Rectorseal #5 and tightened it with a 18" wrench mostly. No leaks. Then, there's the fuel pumps. If the pump manufacturer finds any sign of Teflon tape in the pump, it voids their warranty. Really? How could it get past the pump strainer? Rectorseal #5 is impervious to oil AND PVC cleaner. Gedt it on your clothes and it is there for life. Which I use exclusively to clean oil burner nozzle asseemblies. I NEVER get leaks on oil fittings when I use Teflon Tape. If I get a leak on a Suntec AV pump, they cost me $50.00. If I charge $100.00 per hour, it costs me $100.00 to go fix a leak. And I've never had a new pump fail. If I bother to try to get credit, its a wash. I just throw in another one anyway.